TECHNICAL SUPPORT DOCUMENT FOR AMMONIA

Water Quality Standards Revisions

for Freshwater Ammonia Criteria

April 2014 – January 2015

Andrea Matzke

Water Quality Standards Specialist

Environmental Solutions, WQ Standards & Assessment

ABOUT THIS DOCUMENT

This document supports revisions to Oregon’s freshwater criteria for ammonia. Associated rulemaking documents are on DEQ’s Rules and Regulations Web page at http://www.oregon.gov/deq/RulesandRegulations/Pages/default.aspx.

ACKNOWLEDGEMENTS

DEQ thanks the following reviewers of this document: Spencer Bohaboy (DEQ), Robert Burkhart (DEQ), Shannon Hubler (DEQ), Carl Nadler (DEQ), Debra Sturdevant (DEQ), Maggie Vandehey (DEQ), and Sarina Jepsen (Xerces Society)

LAST UPDATE | DECEMBER 1, 2014

Contents

About This Document  2

Acknowledgements  2

I. Introduction  4

I.A. Scope of Rulemaking  4

II. Background  4

II.A. National Marine Fisheries Service Jeopardy Decision  4

II.B. EPA Disapproval Action  7

II.C. Stakeholder Discussions  8

III. Technical Basis for Updating Freshwater Ammonia Criteria  9

III.A. General Overview of EPA 2013 Recommendations  9

III.B. Effects to Freshwater Aquatic Life  10

III.C. Mussel and Snail Presence in Oregon  12

III.D. Acute Criteria  13

III.E. Current and Proposed Acute Ammonia Criteria Comparison  14

III.F. Chronic Criteria  15

III.G. Current and Proposed Chronic Ammonia Criteria Comparison  17

IV. Site-Specific Criteria for Ammonia  18

V. Beneficial Uses Affected  19

VI. Implementation  20

VI.A. Determination of Mussels Absent  20

VI.B. Permitting  21

VI.C. Integrated Report  24

VI.D. Total Maximum Daily Load Program  26

Appendix A: EPA Letter to Oregon DEQ  27

Appendix B: Presence of Mussels and Snails in Oregon  31

Appendix C: Comparison of species used to calculate the acute and chronic criteria from EPA 2013 criteria document  35

Appendix D: Ammonia Criteria Tables  37

I. INTRODUCTION

Water quality standards regulations define the water quality goals for a waterbody. These goals designate the use or uses, set criteria necessary to protect the uses, and prevent or limit degradation through antidegradation provisions. In January 2013, the Environmental Protection Agency (EPA) disapproved Oregon’s revised freshwater ammonia criteria that DEQ submitted for approval in 2004. To address this disapproval, DEQ proposes adopting EPA’s latest criteria recommendations that take into account mussel and snail sensitivity to ammonia. The Environmental Quality Commission (EQC) must adopt and EPA must approve the ammonia criteria revisions before the rule amendments become effective for Clean Water Act purposes.

I.A. Scope of Rulemaking

The proposed rules revise Oregon’s freshwater ammonia criteria, aligning the criteria with EPA’s latest recommendations finalized in August 2013. EPA’s recommendations consider unionid mussels’ and non-pulmonate snails’ sensitivity to ammonia. Including mollusks in the national dataset makes the ammonia criteria more stringent than if mollusks were not included. There is flexibility to derive site-specific criteria for ammonia in waterbodies where mussels are not present. However, the proposed rules do not include site-specific criteria for waters without mussels or snails because available information indicates that the current and historical presence of mussels and snails throughout Oregon is expansive (see Appendix B).

The proposed rules would also make minor water quality standards rule corrections and clarifications to:

•  Correct an error in the basin-specific pH standard for the main stem Snake River.

•  Add notes indicating EPA disapproval of the narrative natural conditions criterion under OAR 340-041-0007(2) and the natural conditions criterion for temperature under OAR-340-041-0028(8).

•  Amend the Umatilla Basin-specific standards and uses to incorporate EPA’s partial disapproval of DEQ’s site-specific criteria and use designations for the West Division Main Canal.

See additional information about these corrections in the Public Notice document accompanying this rulemaking: http://www.oregon.gov/deq/RulesandRegulations/Pages/default.aspx

II. BACKGROUND

II.A. National Marine Fisheries Service Jeopardy Decision

When the EQC adopts water quality standards, DEQ must submit the criteria to EPA for approval. Section 7(a)(2) of the Endangered Species Act requires federal agencies, including EPA, to consult with the U.S. Fish and Wildlife Service and National Marine Fisheries Service, as appropriate, to ensure that its actions, such as approval of DEQ water quality standards, are not likely to jeopardize the continued existence of endangered or threatened species or adversely modify or destroy their designated critical habitats.

NMFS jurisdiction includes protecting ocean species such as salmon and steelhead and mammals, such as killer whales and seals. ESA action areas for NMFS’s consultation included the freshwater, estuarine and ocean areas under the State of Oregon’s jurisdiction where the criteria apply and areas beyond the state’s jurisdiction where the regulated pollutants could be transported.

The NMFS Biological Opinion¹ dated Aug. 14, 2012 contained an analysis of criteria that Oregon adopted in 2004 for 20 toxic pollutants² associated with 39 freshwater criteria and 26 saltwater criteria, including ammonia criteria. The ammonia criteria that DEQ adopted in 2004 were based on the latest EPA recommendations from 1999.

NMFS concluded that the following Oregon criteria would cause “jeopardy” to many Oregon anadromous salmon and trout species³, in addition to Southern Resident killer whales (based on a long-term, permanent reduction in primary prey—Chinook salmon): (1) ammonia: acute and chronic; (2) copper: acute and chronic; (3) cadmium: acute; and (4) aluminum⁴: acute and chronic. “Jeopardy” means that NMFS found that Oregon’s aquatic life toxics criteria would likely jeopardize the continued existence of threatened and endangered species in Oregon or likely to destroy or adversely modify designated critical habitat. DEQ will address NMFS’s jeopardy decisions associated with EPA disapproval for copper, cadmium and aluminum in future rulemakings.

NMFS recommended that EPA disapprove Oregon’s acute and chronic ammonia criteria that Oregon submitted for approval based on the 1999 EPA recommendations. NMFS’s Reasonable and Prudent Alternatives in its Biological Opinion indicated that EPA should retain Oregon’s currently effective chronic criteria based on 1985 EPA recommendations and to use the “specific process”⁵ described below, along with other considerations, to derive acute criteria for ammonia.

Process for Deriving Criteria

1)  “Only use toxicity data for ammonia, cadmium, and aluminum that is specific to salmonid fishes (if new information becomes available for these compounds for green sturgeon and eulachon, then EPA shall include this data in its analysis);

2)  All toxicity data used to derive the numeric criteria must be curve-fitted, where the literature provides the necessary data to perform this step;

3)  When available, the curve-fitted toxicity data must be used to extrapolate threshold acute and chronic toxic effect concentrations;

4)  Derived criteria must be model-adjusted to account for chemical mixtures; and,

5)  An appropriate population model must be applied to the derived criteria, and must predict no negative change in the intrinsic population growth rate (e.g., lambda, λ).”

The NMFS opinion further states that EPA will ensure the new revised criteria will be effective within 24 months after EPA’s final action to approve or disapprove Oregon’s proposed water quality criteria under the Clean Water Act.

EPA and NMFS are currently discussing how the EPA latest August 2013 ammonia recommendations follow the specific process above.

The U.S. Fish and Wildlife Service, in their July 30, 2012 Biological Opinion, did not find jeopardy with Oregon’s toxics criteria, including ammonia. The USFWS’s jurisdiction includes protecting threatened and endangered freshwater aquatic species such as mollusks, Bull Trout, Oregon Chub, Lost River and Shortnose Suckers.

II.B. EPA Disapproval Action

On Jan. 31, 2013, following NMFS’s Biological Opinion, EPA took action⁶ on Oregon’s new or revised aquatic life toxics criteria submitted in 2004. Among other disapprovals for aquatic life criteria, EPA disapproved the acute and chronic freshwater criteria for ammonia because new toxicity data showed that the criteria were not protective of mollusks.

Oregon adopted EPA’s 1999 national criteria recommendations for ammonia in 2004. At that time, the 1999 recommendations were based on the latest science—toxicity to salmonids and bluegill sunfish. However, new toxicity data based on mollusks became available and formed the basis of EPA’s 2009 proposed national recommendations. EPA based the proposed criteria on the presence or absence of mollusks.⁷ These criteria were more stringent than the 1999 recommendations. Since the publication of the 2009 draft criteria, additional toxicity data on the effect of ammonia to gill-bearing (non-pulmonate) snails further validated toxicity to sensitive snails and mussels in the Unionidae family. In August 2013⁸, EPA finalized its freshwater ammonia recommendations based on gill-bearing snails and unionid mussel sensitivity. These criteria supersede EPA’s 1999 and 2009 recommendations.

EPA acted on Oregon’s ammonia criteria prior to publishing the new 2013 recommendations; therefore, EPA specified the following remedies as options to address its disapproval of Oregon’s ammonia criteria in its determination to DEQ:

“1. Revise the adopted ammonia criteria to be consistent with the 2009 draft revised national recommendations for ammonia criteria.

2. Revise the ammonia criteria to ensure protection of Oregon’s designated aquatic life uses. Also supply a sound scientific rationale to explain why the alternative ammonia criteria are protective of Oregon’s designated aquatic life uses, taking into account any data on freshwater mussels and snails. Finally, to the extent that the adopted chronic aquatic life criterion for ammonia is less stringent than that specified by the National Marine Fisheries Services (“NMFS”) to avoid jeopardy to listed species (i.e., less stringent than the value specified as a “Reasonable and Prudent Alternative” in the NMFS’s August 14, 2012 biological opinion), provide additional sound scientific rationale to establish that the alternative chronic aquatic life criterion for ammonia is protective of Oregon’s designated aquatic life uses, given NMFS’s opinion of the effect of ammonia on Oregon’s listed species.”

DEQ proposes rules to revise criteria that most closely align with remedy 2 above and to base the criteria on the most recent scientific information on ammonia toxicity in the 2013 EPA recommendations. Although states have the discretion to adopt criteria different from EPA’s national recommendations, DEQ does not believe there is a benefit in conducting additional toxicity studies or re-evaluating the toxicity studies supporting the updated EPA criteria to derive alternate criteria. As stated earlier, EPA and NMFS are evaluating how EPA’s latest 2013 recommendations are consistent with the “specific process” (see section II.A) described in the Reasonable and Prudent Alternatives in NMFS’s jeopardy opinion. If NMFS determines that EPA’s criteria derivation method generally followed the Reasonable and Prudent Alternatives, then NMFS can conclude that EPA’s 2013 ammonia criteria protect threatened and endangered species in Oregon, thus satisfying ESA consultation requirements. A “no jeopardy” decision from NMFS would likely lead to EPA approval of Oregon’s proposed ammonia criteria.

II.C. Stakeholder Discussions

Prior to initiating rulemaking, DEQ sent an invitation to Oregon tribes and to a wide range of stakeholders to discuss and provide input to DEQ on rulemaking priorities to address EPA disapproved criteria for aluminum, ammonia, cadmium (acute) and copper. DEQ staff and stakeholders (Table 1) met in January and February of 2014. During these meetings, DEQ also shared information about EPA’s updated criteria for freshwater copper and ammonia.

Table 1: Stakeholder List

Generally, staff and stakeholders support adopting the new EPA ammonia criteria recommendations as quickly as possible. Dischargers indicated that having up-to-date approvable criteria would resolve uncertainty about which ammonia criteria Oregon and EPA would ultimately recommend. These uncertainties have existed since 2004, particularly in issuing NPDES permits.

EPA supports Oregon’s revisions to its ammonia criteria as soon as possible. On May 16, 2014, EPA Region 10 sent correspondence to Wendy Wiles, Administrator, Environmental Solutions Division. The correspondence urges Oregon to evaluate EPA’s latest 2013 ammonia recommendations as part of DEQ’s next triennial review. See Appendix A.

III. TECHNICAL BASIS FOR UPDATING FRESHWATER AMMONIA CRITERIA

III.A. General Overview of EPA 2013 Recommendations

This section summarizes information from EPA’s 2013 ammonia recommendations:

•  Final Aquatic Life Ambient Water Quality Criteria For Ammonia—Freshwater 2013 in the Federal Register⁹ dated Aug. 22, 2013.

•  Aquatic Life Ambient Water Quality Criteria for Ammonia – Freshwater 2013¹⁰. This publication, hereafter called “EPA 2013 Criteria Document,” provides detailed information about the derivation of the revised criteria.

The two documents above and other implementation documents are on EPA’s website at http://water.epa.gov/scitech/swguidance/standards/criteria/aqlife/ammonia/index.cfm.

EPA’s methodology for assessing toxicity data in deriving updated ammonia criteria followed EPA’s “Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses” (Stephan et al. 1985.) This is EPA’s current guideline for deriving aquatic life toxics criteria.

The updated ammonia criteria, expressed as Total Ammonia Nitrogen, include ammonium (NH₄) and unionized ammonia (NH₃). Starting with its 1999 recommendation, EPA recommended a TAN expression of the ammonia criteria. EPA’s 2013 Criteria Document states that because permit limits and compliance are usually expressed in terms of TAN given the toxicity of both forms of ammonia, expressing the criterion in terms of TAN eliminates the need to convert to and from unionized ammonia.

Both pH and temperature affect the toxicity of ammonia. Generally, as pH and temperature increase, the amount of unionized ammonia, the more toxic form of ammonia, predominates. Therefore, the criteria are more stringent as pH and temperature rise. Oregon expresses its current ammonia criteria, based on EPA’s 1985 recommendations, as unionized ammonia. This requires specific calculations to adjust for temperature and pH, and then converting to TAN.

EPA bases the updated ammonia criteria on additional data showing the toxicity of ammonia to freshwater mussels in the family Unionidae and to gill-bearing (non-pulmonate) snails. Because unionid mussels and gill-bearing snails are in many freshwater systems throughout the United States, EPA recommended applying the acute and chronic criteria based on the assumption that these sensitive species are present in waterbodies throughout the country. This is in contrast to the 2009 draft recommendations that proposed a bifurcated approach—separate criteria based on mussels present or absent. DEQ may develop site-specific criteria based on the absence of mussels if a defensible mussel survey indicates mussels are not present. For more information about site-specific criteria, see Section IV. EPA removed six invasive/non-native species, such as Asiatic clams, from the national dataset based on comments received in response to the draft 2009 ammonia recommendations. Therefore, the proposed criteria protect species native to the United States.

EPA also renormalized the data based on a pH of 7 and a temperature of 20˚C to be more representative of freshwater systems. EPA does not recommend extrapolating criteria values outside the pH ranges shown in the ammonia criteria tables in Appendix D (i.e. 6.5 – 9.0) which represent the normal range of freshwaters.

EPA’s acute criteria also consider presence or absence of salmonids. The presence of early life stages of fish in applying the chronic criteria is not applicable because the chronic dataset shows that mussels are more sensitive than any other early life fish species tested. Table 2 below contains summary information on how EPA applies the criteria, as well as the associated table reference for where the criteria and associated formulas are found in Appendix D.

 Table 2: Criteria Application Summary

*Highest 4-day average within the 30-day averaging period must not be more than 2.5 times the chronic value

III.B. Effects to Freshwater Aquatic Life

Ammonia is a naturally occurring pollutant commonly found in waste products and fertilizers. Its presence can cause toxicity to aquatic life. Specific sources include:

•  Municipal and industrial waste

•  Septic system seepage

•  Fertilizer runoff from agricultural and urban sources

•  Manure application

•  Concentrated animal feeding operations

•  Aquaculture

•  Landfill leachate

EPA conducted literature reviews from 1985 through October 2012 on the effects of ammonia to aquatic life. This search resulted in a large dataset that met EPA’s 1985 Guidelines minimum data requirements for all eight taxa for both acute and chronic datasets. For the acute dataset, the four most sensitive species to ammonia are mussels in the Unionidae family. There are also several mussel species among the four most sensitive species in the chronic dataset. Table 3 below is reproduced from EPA’s 2013 Criteria Document and describes the effects of ammonia on fish, invertebrates and bivalves.

Table 3: Effects of Ammonia on Fish and Invertebrates

The ammonia assessment was EPA’s first explicit analysis of ESA-listed species in a criteria document. The national dataset includes fourteen threatened and endangered species including five mussels. EPA’s analysis did not identify any of the listed species as the most sensitive species. However, the inclusion of listed species in deriving nationally recommended criteria does not remove ESA consultation requirements when a state submits its revised water quality standards to EPA for approval.

III.C. Mussel and Snail Presence in Oregon

Mussels and snails are important to food webs, water quality, nutrient cycling and habitat quality in freshwater systems. According to Freshwater Mussels of the Pacific Northwest,¹¹ freshwater mussels are one of the most endangered groups of animals on Earth. Of the nearly 300 North American species, 35 have gone extinct in the last 100 years. ESA also lists nearly 25 percent as endangered or threatened and individual states list 75 percent as endangered, threatened or of special concern. The western part of the U.S. has a very low diversity compared to the 290 species that occur in the eastern two-thirds of North America.

Xerces Society data¹² indicates there are six species of mussels in Oregon and DEQ data sources indicate there are approximately 16 species or taxa of snails in Oregon. Table 4 below lists these species. Currently, ESA does not list any of these species as threatened or endangered.

 Table 4: Mussel and snail species present in Oregon

Although EPA used mussel toxicity data from specific species in the Unionidae family, the intent of the 2013 ammonia criteria is to protect the aquatic community as a whole even if mussels from the Unionidae family are absent, but other non-Unionidae mussels are present at a site. The Unionid species serve as surrogates for freshwater mussels in general and are not just representative of the family Unionidae.  For example, all the mussels listed above with the exception of Margaritifera falcata are in the Unionidae family. Margaritifera falcata is in the Margaritiferidae family. If there are Oregon locations where there are species from the Margaritiferidae family and not the Unionidae family, the criteria dataset would still need to retain the toxicity data for the Unionidae mussels to protect all freshwater mussels.¹³ 

Maps in Appendix B show where mussels and snails occur or where historical information has documented presence in Oregon. As illustrated by these maps, most watersheds in Oregon contain or historically contained some species of mussel or snail. For this reason, DEQ does not see a compelling reason to propose site-specific criteria for waterbodies where mollusks may not be present as part of this rulemaking. See site-specific criteria development in Section IV for more information.

III.D. Acute Criteria

EPA included 120 acute studies in its derivation of acute criteria. There were 69 genera representing 52 invertebrates, 44 fish and 4 amphibians. The four species and the genus mean acute value (GMAV)¹⁴ associated with each tested species from most to least sensitive are:

1. Lasmigona subviridis, Green Floater (GMAV= 23.41 mg TAN/L)

2. Epioblasma capsaeformis, Oyster mussel (GMAV= 31.14 mg TAN/L)

3. Villosa iris, Rainbow Mussel (GMAV= 34.23 mg TAN/L)

4. Lampsilis sp. (GMAV=46.63 mg TAN/L)

Although mussels are the most sensitive species in the dataset, at temperatures below 15.7°C, salmonid¹⁵ sensitivity determines the acute criterion regardless of pH as shown in Figure 1. Appendix C, Table 1 compares sensitive species and associated acute criteria for EPA recommendations in 1999, 2009 and 2013.

Figure 1: Salmonid sensitivity at lower temperatures

The frequency and duration of the acute criteria did not change from previous EPA recommendations. The one-hour average concentration of total ammonia nitrogen (in mg TAN/L) is not to be exceeded more than once every three years on average. At a pH of 7 and a temperature of 20˚C, the acute criterion is 17 mg/L TAN. For criteria based on different pH and temperatures, salmonids present and absent, and associated criteria equations, see Tables 1 and 2 in Appendix D.

III.E. Current and Proposed Acute Ammonia Criteria Comparison

Generally, EPA’s updated acute criteria are more stringent than Oregon’s current criteria, which DEQ based on EPA recommendations from 1985. However, at lower temperatures and pH, EPA’s criteria are less stringent than Oregon’s current acute criteria. Figure 2 below illustrates the difference in criteria at selected pH values and the presence of salmonids. Trout and salmon inhabit many waterbodies throughout Oregon.

Figure 2: Comparison between current and proposed acute ammonia criteria

III.F. Chronic Criteria

Ammonia chronic toxicity data were available for 21 species of freshwater organisms: 10 invertebrate species (mussels, clam, snail, cladocerans, daphnid and insect) and 11 fish species, including three federally listed salmonid species.

EPA calculated the chronic criterion based on the fifth percentile of the genus mean chronic values (GMCV) of the 21 tested species. The GMCVs for the four most sensitive species from most to least sensitive are:

1. Lampsilis spp, Wavy-rayed lamp mussel and Fatmucket (GMCV=2.126 mg TAN/L)

2. Villosa iris, Rainbow mussel (GMCV= 3.501 mg TAN/L)

3. Lepomis spp., Bluegill and Green sunfish (GMCV= 6.920 mg TAN/L)

4. Musculium transversum, Long fingernailclam (GMCV= 7.547 mg TAN/L)

The chronic dataset ranks the pebblesnail as number five. Insects were the least sensitive in the chronic data, while salmonids had middle sensitivities. Because EPA based the chronic criteria on the effects of sensitive invertebrate species, including unionid mussels when mussels are present, the chronic criteria are protective of early life fish stages regardless of temperature. For this reason, criteria calculations to account for presence or absence of fish early life stages are not necessary. See Appendix C, Table 2 for comparisons of sensitive species and associated chronic criteria in the EPA recommendations from 1999, 2009 and 2013.

The chronic averaging period changed from Oregon’s current 1985 recommendations averaging period of 4 days to a period of 30 days. EPA recommended this change beginning with the 1999 update, although EPA allowed a 30-day averaging period in the 1985 recommendations if concentrations of ammonia had limited variability. EPA indicates that a 30-day averaging period continues to be appropriate, but that a 4-day averaging period is also necessary to align with the duration exposure specified in the 1985 Stephan et al Guidelines for chronic criteria, and as a basis for water quality based effluent limits. Further, it provides a limit in variability of ammonia concentrations. Based on 7-day toxicity tests on fathead minnows, EPA determined that the highest 4-day average within a 30-day period should not exceed 2.5 times the chronic criterion at a certain pH and temperature¹⁶. Therefore, if the chronic criterion at a pH of 7 and temperature of 20˚C is 1.9 mg/L TAN, the highest 4-day average within that 30 day period cannot exceed 4.8 mg/L TAN (i.e. 1.9 x 2.5). For criteria based on different pH and temperatures, including criteria formulas, see Table 3 in Appendix D. Figure 3 below shows the EPA’s chronic criteria at selected pH values.

Figure 3: Proposed chronic criteria at selected pH values

III.G. Current and Proposed Chronic Ammonia Criteria Comparison

Generally, EPA’s updated chronic criteria are less stringent than Oregon’s current criteria based on EPA recommendations from 1985. Figure 4 below illustrates the difference in criteria at selected pH values. Since Oregon’s current criteria do not use 30-day averaging, DEQ multiplied EPA criteria values at selected pH values by 2.5 (i.e. any 4-day average in a 30-day period cannot exceed 2.5 times the chronic criterion) to compare to Oregon’s criteria based on a 4-day average. Figure 5 directly compares Oregon’s criteria based on a 4-day average to EPA’s criteria based on a 30-day average. The Figure 5 comparison shows that the criteria differences are not as great.

Figure 4: Comparison between current and proposed chronic ammonia criteria

Note: The graph above shows Oregon’s ammonia chronic criteria at pH of 6.5 and 7.0 on one line because they are almost identical. The graph shows Oregon’s criteria based on salmonid presence. Presence or absence of salmonids is not applicable for the proposed chronic criteria.

Figure 5: Comparison between current and proposed chronic ammonia criteria

Note: The graph above shows Oregon’s ammonia chronic criteria at pH of 6.5 and 7.0 on one line because they are almost identical. The graph shows Oregon’s criteria based on salmonid presence. Presence or absence of salmonids is not applicable for the proposed chronic criteria.

IV. SITE-SPECIFIC CRITERIA FOR AMMONIA

Similar to other water quality pollutants, Oregon may develop site-specific criteria for ammonia where there are demonstrated differences in sensitivity between the aquatic species that occur at the site and those used to derive the national criteria recommendations. The analysis must be based on a sound scientific rationale that protects the designated use and is subject to EPA review and approval.

In Appendix N of EPA’s 2013 Criteria Document, EPA provided a species recalculation of the ammonia criteria where there are no mussels and there are no species at a site related to unionid mussels. EPA provided these alternate criteria due to the complexity of the relationship between ammonia toxicity and pH and temperature across different aquatic organisms. The removal of mussels from the national dataset results in criteria that are less stringent, but remain protective of the aquatic community residing at a site.

The procedure associated with removing mussels from the national dataset is the Recalculation Procedure¹⁷. The procedure:

•  Allows deletion of nonresident tested species from the national dataset if they are not appropriate surrogates of resident untested species. Alternatively, the procedure could account for unique species at a waterbody site that EPA’s national dataset did not represent. A state can then derive site-specific criteria to protect the aquatic species found at a particular site.

•  May result in site-specific criteria that are either more or less stringent than EPA’s recommended criteria

For more information about the Recalculation Procedure, see EPA’s updated guidance: http://water.epa.gov/scitech/swguidance/standards/criteria/aqlife/ammonia/upload/Revised-Deletion-Process-for-the-Site-Specific-Recalculation-Procedure-for-Aquatic-Life-Criteria.pdf.

As noted earlier, EPA must approve site-specific criteria. Any revised or new criteria/site-specific criteria proposed to protect aquatic life are also subject to ESA consultation requirements, which can complicate development of protective criteria. For example, EPA used toxicity data associated with salmonid species listed as threatened or endangered in Oregon in deriving national protective ammonia criteria, generally developed to protect 95 percent of aquatic species. If a discharger or other third party demonstrated that mussels were not present at a site and proposed site-specific criteria, EPA would still need to consult with NMFS and USFWS to assure protectiveness of any threatened or endangered species residing in Oregon. In addition, the biological assessments from NMFS, USFWS and EPA may have conflicting conclusions because of the differences in how NMFS and USFWS assess biological assessment data in comparison to EPA established methodologies in deriving national criteria.

V. BENEFICIAL USES AFFECTED

Criteria for ammonia apply to waterbodies where the “fish and aquatic life” beneficial use is designated. In addition, a different set of acute ammonia criteria apply to a waterbody based on the presence or absence of salmonids¹⁸.

The fish use subcategories bulleted below include salmonid uses for Oregon waterbodies. Where any of these subcategories is a designated use for a waterbody, the more stringent ammonia criteria based on the presence of salmonids apply. The majority of Oregon’s waterbodies support salmonid use.

•  Bull trout spawning and juvenile rearing

•  Core cold-water habitat

•  Salmon and trout rearing and migration

•  Salmon and steelhead migration corridor

•  Redband or Lahontan Cutthroat Trout

Where salmonids are not a designated use, the stream’s designated use is for either cool water species or Borax Lake chub. These areas include highly alkaline and saline lakes in Goose and Summer Lake subbasin, the lower portions of the Klamath, Malheur and Owyhee Rivers and a few other stream reaches, as shown on the fish use tables and maps at the link below. The less stringent acute criteria would apply in these waterbodies.

Because chronic toxicity tests show mussels are more sensitive than salmonid species, EPA did not need to develop chronic criteria to specifically protect early life stages of salmonids. In the situation where a site-specific chronic criterion is developed for ammonia based on mussels absent, then protection of early life stages of fish is necessary. Most waterbodies in Oregon support early life stages of fish.

Access fish use maps for Oregon here: http://www.deq.state.or.us/wq/standards/uses.htm.

VI. IMPLEMENTATION

VI.A. Determination of Mussels Absent

DEQ proposes to adopt EPA’s criteria that protect mussels from ammonia impacts. Section IV describes the process to develop site-specific criteria when mussels are absent. This section briefly describes important considerations in EPA’s Recalculation Procedure that DEQ would likely follow in evaluating cases where a third party requested site-specific criteria based on the absence of mussels.

Since EPA’s Recalculation Procedure is dependent on what species occur at a site, it is important to distinguish a species being “resident” from a species “occurring at a site.” EPA makes this distinction in the Revised Deletion Process for the Site-Specific Recalculation Procedure for Aquatic Life Criteria¹⁹:

“The terms “resident” and “occur at the site” include life stages and species that meet one of the following elements:

•  Are usually present at the site

•  Are present at the site only seasonally due to migration

•  Are present at the site intermittently because they periodically return to or extend their ranges into the site

•  Were present at the site in the past, are not currently present at the site due to degraded conditions, but are expected to return to the site when conditions improve, or

•  Are present in nearby bodies of water, are not currently present at the site due to degraded conditions, but are expected to be present at the site when conditions improve.

The terms “resident” or “occur at the site” do not include life stages and species that meet one of the following elements:

•  Were once present at the site but cannot exist at the site now due to permanent (physical) alterations of the habitat or other conditions that are not likely to change within reasonable planning horizons.

•  Are still-water life stages or species that are found at a flowing-water site solely and exclusively because they are washed through the site by stream flow from a still-water site.”

EPA’s Technical Support Document for Conducting and Reviewing Freshwater Mussel Occurrence Surveys for the Development of Site-specific Water Quality Criteria for Ammonia²⁰ describes methods and approaches for conducting mussel surveys. EPA does not endorse one survey method over another, but the survey method must support a scientifically defensible rationale to demonstrate that mussels do not occur at a site.

This rulemaking does not recommend a specific mussel survey method for the purpose of potentially developing site-specific criteria for ammonia. If a discharger or other third party believes mussels may not be present at a site, methodologies described in EPA’s document above would likely meet the scientific rigor needed to establish presence or absence of mussels. Other scientifically acceptable methods, such as those developed by Oregon Department of Fish and Wildlife, U.S. Fish and Wildlife Service or the Xerces Society may meet survey objectives. If needed, DEQ may develop guidance on conducting mussel surveys following adoption of revised ammonia criteria.

VI.B. Permitting

The ammonia criteria are temperature and pH dependent, requiring that data for these physical parameters are available for both the effluent and the receiving water body. As temperature increases, the total ammonia criterion becomes progressively lower (more stringent), which can result in restrictive discharge limitations. However, the criterion at low temperatures can also be limiting because biological treatment of ammonia (NH₃ to NO₃ to N₂) is more difficult at low temperatures.

The proposed acute criteria are generally more stringent than Oregon’s current ammonia criteria, while the proposed chronic criteria are generally less stringent than Oregon’s current criteria. Due to anti-backsliding rules, in cases where the proposed ammonia criteria result in effluent limits that are less restrictive than the current limits, DEQ would typically preserve the more stringent limits. There are some exceptions to this policy, including:

•  EPA approved Total Maximum Daily Load and the TMDL contains less stringent effluent limitations than the permittee’s current effluent limits, or

•  Environmental Quality Commission approved pollutant load increase provided the increase is consistent with Clean Water Act 303(d)(4) or

•  Permit meets one of the exceptions in CWA 402(o)(2).

The implementation of the proposed water quality criteria will not affect the National Pollutant Discharge Elimination System general permits because there are no ammonia limit requirements in these permits. There is an ammonia reference limit of 10 mg/L for the industrial stormwater permit (1200-Z) based on an EPA limit rather than state water quality standards. In the situation where a 1200Z permit holder discharges to a stream impaired for ammonia, DEQ would base the benchmark on the state water quality standard. Therefore, a revision to the state’s ammonia criteria may affect 1200Z permits discharging to waterbodies currently impaired for ammonia or for future impairment listings.

The implementation of the proposed water quality criteria would affect the individual NPDES permit development process and permit requirements for design flows and monitoring requirements.

Design Flows

A typical part of the permit development process is to assess whether the effluent discharge has an effect on the receiving water body. DEQ typically evaluates this impact by conducting a reasonable potential analysis.

Currently, DEQ uses the following receiving stream design flows for the aquatic life toxics acute and chronic evaluation:

•  Acute Criterion:  1Q10²¹

•  Chronic Criterion:  7Q10²²

EPA recommends use of one of the following design flows for determining compliance with the proposed acute and chronic ammonia criteria:

•  Acute Criterion:  1B3²³ or 1Q10¹⁹

•  Chronic Criterion:  30B3²⁴, 30Q10²⁵ or 30Q5²⁶

DEQ anticipates continuing use of the 1Q10 design flow to determine compliance with the proposed acute ammonia criteria. Depending upon the design flow selected for compliance with the chronic criteria, DEQ may require facilities to update their mixing zone studies to reflect the necessary design flow appropriately.²⁷ DEQ has not yet determined which design flow it will use to determine compliance with the proposed chronic criteria. If DEQ uses the 30Q5 design flow, which it currently uses to determine compliance with non-carcinogenic human health toxics criteria, it is likely that dischargers will not need to revise most mixing zone analyses²⁸. However, if DEQ determines that one of the other design flows was more appropriate, it is likely that dischargers will need to revise current mixing zone analyses.

According to the EPA²⁹, if DEQ recommends using the 30Q5 flow to determine reasonable potential for the chronic ammonia criterion, the permit writer will need to ensure that the 7Q10 flow is protective of 2.5 times the chronic criterion, so that any short term, 4-day, flow variability within the 30-day averaging period does not lead to shorter-term chronic toxicity. If DEQ uses the 30B3 or the 30Q10 flow in the reasonable potential determination, the permit writer will not need to conduct this analysis.

Monitoring Requirements

There are currently two types of effluent monitoring required under NPDES permits. The first is characterization monitoring used in developing a permit to determine whether effluent limits are required. If effluent limits are required and subsequently included in an NPDES permit, DEQ then requires compliance monitoring to determine whether the discharger is meeting its effluent limits. The amount of monitoring required for both characterization and compliance monitoring varies based upon a facility’s average design flows. For example, permits for larger facilities require more monitoring.

For characterization purposes, there is the potential that DEQ will require additional monitoring requirements for smaller facilities to ensure that there is sufficient data to adequately characterize the effluent and allow for averaging within a 30-day period. Additional data points will better characterize the discharge, minimize statistical error associated with the reasonable potential analysis, and help identify outliers.

Similarly, where DEQ establishes an ammonia effluent limit, DEQ may require additional compliance monitoring to demonstrate that “no 4-day average concentrations should exceed 2.5 times the chronic criterion.”

VI.C. Integrated Report

Every two years, the Clean Water Act requires DEQ to assess water quality and report on the condition of Oregon's waters. DEQ prepares an Integrated Report that meets the requirements of the CWA for section 305(b) and section 303(d). Section 305(b) requires a report on the overall condition of Oregon's waters, while section 303(d) requires identifying waters that do not meet water quality standards and where DEQ needs to develop a Total Maximum Daily Load, TMDL, pollutant load allocation.

DEQ may:

•  Add waterbodies to the 303(d) list, Category 5, based on the evaluation of new data, application of new or revised water quality standards, or information showing water quality has declined.

•  Remove waterbodies from the 303(d) list when Oregon establishes TMDLs or other control measures, Categories 4A and 4B, respectively, that DEQ expects to improve water quality when data show water quality has improved.

•  Remove waterbodies when Oregon revises water quality standards and data indicate that the waterbody is now attaining water quality standards.

The proposed ammonia criteria may affect current 303(d) listings for ammonia. DEQ’s Integrated Report staff use the chronic criteria for ammonia to evaluate whether waterbodies are meeting state water quality standards. Based on the published 2010 Integrated Report, there are 15 waterbodies impaired for ammonia listed in Table 5. Five waterbodies need TMDLs and ten waterbodies have approved TMDLs or other control measures in place. Because DEQ expects the proposed chronic criteria to be less stringent than Oregon’s current chronic criteria for ammonia, DEQ may propose to delist waterbodies where there are current 303(d) listings if data shows that these waterbodies now meet ammonia criteria. DEQ will reassess waterbodies using the new ammonia criteria in the next cycle of the Integrated Report following EPA approval.

 Table 5: Waterbodies Listed for Ammonia Based on the 2010 Integrated Report

VI.D. Total Maximum Daily Load Program

A Total Maximum Daily Load (TMDL) is a calculation of the maximum amount of a pollutant that a waterbody can receive and still safely meet water quality standards. If DEQ includes a waterbody on the 303(d) list, DEQ must develop a TMDL, or other control measures in limited circumstances, to bring the waterbody back into compliance by meeting water quality standards. Through an extensive evaluation, DEQ develops pollutant allocations for point and nonpoint sources for the pollutant of concern.

As indicated in Table 5 above, several waterbodies need TMDLs for ammonia listings. In addition, there are a number of waterbodies where DEQ has already developed TMDLs to address ammonia impairments. Following adoption and subsequent EPA approval of revised ammonia criteria, DEQ will likely need to re-assess wasteload and load allocations that DEQ developed for existing ammonia TMDLs to evaluate whether the existing pollutant allocations are still appropriate. For example, it is not yet clear whether Waste Load Allocations will be based on the chronic 30-day rolling average, the 2.5 times the chronic criterion four-day average within the 30-day rolling average, or even the acute criteria duration based on a one-hour average. Waste load allocations may need to be based on both, with different compliance averaging periods. For example, DEQ could base one waste load allocation on a maximum monthly four-day average and the other on a maximum one-day average.

APPENDIX A: EPA LETTER TO OREGON DEQ

APPENDIX B: PRESENCE OF MUSSELS AND SNAILS IN OREGON

Oregon Snail Presence

DEQ database

WMC database

Pulmonate snails

DEQ database

WMC database

Non-pulmonate (gilled) snails

WMC = Western Monitoring Center

APPENDIX C: COMPARISON OF SPECIES USED TO CALCULATE THE ACUTE AND CHRONIC CRITERIA FROM EPA 2013 CRITERIA DOCUMENT

APPENDIX D: AMMONIA CRITERIA TABLES

AMMONIA FRESHWATER CRITERIA TABLES

DEQ based the following proposed Tables 30(a)-(c) on EPA’s April 2013 document, Aquatic Life Ambient Water Quality Criteria for Ammonia – Freshwater 2013, Office of Water (EPA 822-R-13-001.).

Table 30(b): Ammonia Acute Criteria Values (One-hour Average*)—Salmonid Species Absent Temperature and pH-Dependent and expressed as Total Ammonia Nitrogen (mg/L TAN)
Criteria cannot be exceeded more than once every three years
Acute Criterion=0.7249 × 0.01141+107.204-pH+1.61811+10pH-7.204×MIN51.93, 23.12×100.036×20-T
Temperature (oC)
pH		0-10		11		12		13		14		15		16			17		18		19		20		21		22		23			24		25		26		27		28		29		30
6.5		51		48		44		41		37		34		32			29		27		25		23		21		19		18			16		15		14		13		12		11		9.9
6.6		49		46		42		39		36		33		30			28		26		24		22		20		18		17			16		14		13		12		11		10		9.5
6.7		46		44		40		37		34		31		29			27		24		22		21		19		18		16			15		14		13		12		11		9.8		9.0
6.8		44		41		38		35		32		30		27			25		23		21		20		18		17		15			14		13		12		11		10		9.2		8.5
6.9		41		38		35		32		30		28		25			23		21		20		18		17		15		14			13		12		11		10		9.4		8.6		7.9
7.0		38		35		33		30		28		25		23			21		20		18		17		15		14		13			12		11		10		9.4		8.6		7.9		7.3
7.1		34		32		30		27		25		23		21			20		18		17		15		14		13		12			11		10		9.3		8.5		7.9		7.2		6.7
7.2		31		29		27		25		23		21		19			18		16		15		14		13		12		11			9.8		9.1		8.3		7.7		7.1		6.5		6.0
7.3		27		26		24		22		20		18		17			16		14		13		12		11		10		9.5			8.7		8.0		7.4		6.8		6.3		5.8		5.3
7.4		24		22		21		19		18		16		15			14		13		12		11		9.8		9.0		8.3			7.7		7.0		6.5		6.0		5.5		5.1		4.7
7.5		21		19		18		17		15		14		13			12		11		10		9.2		8.5		7.8		7.2			6.6		6.1		5.6		5.2		4.8		4.4		4.0
7.6		18		17		15		14		13		12		11			10		9.3		8.6		7.9		7.3		6.7		6.2			5.7		5.2		4.8		4.4		4.1		3.8		3.5
7.7		15		14		13		12		11		10		9.3			8.6		7.9		7.3		6.7		6.2		5.7		5.2			4.8		4.4		4.1		3.8		3.5		3.2		2.9
7.8		13		12		11		10		9.3		8.5		7.9			7.2		6.7		6.1		5.6		5.2		4.8		4.4			4.0		3.7		3.4		3.2		2.9		2.7		2.5
7.9		11		9.9		9.1		8.4		7.7		7.1		6.6			3.0		5.6		5.1		4.7		4.3		4.0		3.7			3.4		3.1		2.9		2.6		2.4		2.2		2.1
8.0		8.8		8.2		7.6		7.0		6.4		5.9		5.4			5.0		4.6		4.2		3.9		3.6		3.3		3.0			2.8		2.6		2.4		2.2		2.0		1.9		1.7
8.1		7.2		6.8		6.3		5.8		5.3		4.9		4.5			4.1		3.8		3.5		3.2		3.0		2.7		2.5			2.3		2.1		2.0		1.8		1.7		1.5		1.4
8.2		6.0		5.6		5.2		4.8		4.4		4.0		3.7			3.4		3.1		2.9		2.7		2.4		2.3		2.1			1.9		1.8		1.6		1.5		1.4		1.3		1.2
8.3		4.9		4.6		4.3		3.9		3.6		3.3		3.1			2.8		2.6		2.4		2.2		2.0		1.9		1.7			1.6		1.4		1.3		1.2		1.1		1.0		0.96
8.4		4.1		3.8		3.5		3.2		3.0		2.7		2.5			2.3		2.1		2.0		1.8		1.7		1.5		1.4			1.3		1.2		1.1		1.0		0.93		0.86		0.79
8.5		3.3		3.1		2.9		2.7		2.4		2.3		2.1			1.9		1.8		1.6		1.5		1.4		1.3		1.2			1.1		0.98		0.90		0.83		0.77		0.71		0.65
8.6		2.8		2.6		2.4		2.2		2.0		1.9		1.7			1.6		1.5		1.3		1.2		1.1		1.0		0.96			0.88		0.81		0.75		0.69		0.63		0.58		0.54
8.7		2.3		2.2		2.0		1.8		1.7		1.6		1.4			1.3		1.2		1.1		1.0		0.94		0.87		0.80			0.74		0.68		0.62		0.57		0.53		0.49		0.45
8.8		1.9		1.8		1.7		1.5		1.4		1.3		1.2			1.1		1.0		0.93		0.86		0.79		0.73		0.67			0.62		0.57		0.52		0.48		0.44		0.41		0.37
8.9		1.6		1.5		1.4		1.3		1.2		1.1		1.0			0.93		0.85		0.79		0.72		0.67		0.61		0.56			0.52		0.48		0.44		0.40		0.37		0.34		0.32
9.0		1.4		1.3		1.2		1.1		1.0		0.93		0.86			0.79		0.73		0.67		0.62		0.57		0.52		0.48			0.44		0.41		0.37		0.34		0.32		0.29		0.27
Table 30(c): Ammonia Chronic Criteria Values (30-day Rolling Average*) Temperature and pH-Dependent and expressed as Total Ammonia Nitrogen (mg/L TAN) * The highest four-day average within the 30-day averaging period must not be more than 2.5 times the chronic value
Criteria cannot be exceeded more than once every three years
Chronic Criterion=0.8876 × 0.02781+107.688-pH+1.19941+10pH-7.688×2.126×100.028×20-MAXT,7
Temperature (oC)
pH	0-7		8		9		10		11		12		13		14	15		16		17		18		19		20		21		22	23		24		25		26		27		28		29		30
6.5	4.9		4.6		4.3		4.1		3.8		3.6		3.3		3.1	2.9		2.8		2.6		2.4		2.3		2.1		2.0		1.9	1.8		1.6		1.5		1.5		1.4		1.3		1.2		1.1
6.6	4.8		4.5		4.3		4.0		3.8		3.5		3.3		3.1	2.9		2.7		2.5		2.4		2.2		2.1		2.0		1.8	1.7		1.6		1.5		1.4		1.3		1.3		1.2		1.1
6.7	4.8		4.5		4.2		3.9		3.7		3.5		3.2		3.0	2.8		2.7		2.5		2.3		2.2		2.1		1.9		1.8	1.7		1.6		1.5		1.4		1.3		1.2		1.2		1.1
6.8	4.6		4.4		4.1		3.8		3.6		3.4		3.2		3.0	2.8		2.6		2.4		2.3		2.1		2.0		1.9		1.8	1.7		1.6		1.5		1.4		1.3		1.2		1.1		1.1
6.9	4.5		4.2		4.0		3.7		3.5		3.3		3.1		2.9	2.7		2.5		2.4		2.2		2.1		2.0		1.8		1.7	1.6		1.5		1.4		1.3		1.2		1.2		1.1		1.0
7.0	4.4		4.1		3.8		3.6		3.4		3.2		3.0		2.8	2.6		2.4		2.3		2.2		2.0		1.9		1.8		1.7	1.6		1.5		1.4		1.3		1.2		1.1		1.1		0.99
7.1	4.2		3.9		3.7		3.5		3.2		3.0		2.8		2.7	2.5		2.3		2.2		2.1		1.9		1.8		1.7		1.6	1.5		1.4		1.3		1.2		1.2		1.1		1.0		0.95
7.2	4.0		3.7		3.5		3.3		3.1		2.9		2.7		2.5	2.4		2.2		2.1		2.0		1.8		1.7		1.6		1.5	1.4		1.3		1.3		1.2		1.1		1.0		0.96		0.90
7.3	3.8		3.5		3.3		3.1		2.9		2.7		2.6		2.4	2.2		2.1		2.0		1.8		1.7		1.6		1.5		1.4	1.3		1.3		1.2		1.1		1.0		0.97		0.91		0.85
7.4	3.5		3.3		3.1		2.9		2.7		2.5		2.4		2.2	2.1		2.0		1.8		1.7		1.6		1.5		1.4		1.3	1.3		1.2		1.1		1.0		0.96		0.90		0.85		0.79
7.5	3.2		3.0		2.8		2.7		2.5		2.3		2.2		2.1	1.9		1.8		1.7		1.6		1.5		1.4		1.3		1.2	1.2		1.1		1.0		0.95		0.89		0.83		0.78		0.73
7.6	2.9		2.8		2.6		2.4		2.3		2.1		2.0		1.9	1.8		1.6		1.5		1.4		1.4		1.3		1.2		1.1	1.1		0.98		0.92		0.86		0.81		0.76		0.71		0.67
7.7	2.6		2.4		2.3		2.2		2.0		1.9		1.8		1.7	1.6		1.5		1.4		1.3		1.2		1.1		1.1		1.0	0.94		0.88		0.83		0.78		0.73		0.68		0.64		0.60
7.8	2.3		2.2		2.1		1.9		1.8		1.7		1.6		1.5	1.4		1.3		1.2		1.2		1.1		1.0		0.95		0.89	0.84		0.79		0.74		0.69		0.65		0.61		0.57		0.53
7.9	2.1		1.9		1.8		1.7		1.6		1.5		1.4		1.3	1.2		1.2		1.1		1.0		0.95		0.89		0.84		0.79	0.74		0.69		0.65		0.61		0.57		0.53		0.50		0.47
8.0	1.8		1.7		1.6		1.5		1.4		1.3		1.2		1.1	1.1		1.0		0.94		0.88		0.83		0.78		0.73		0.68	0.64		0.60		0.56		0.53		0.50		0.44		0.44		0.41
8.1	1.5		1.5		1.4		1.3		1.2		1.1		1.1		0.99	0.92		0.87		0.81		0.76		0.71		0.67		0.63		0.59	0.55		0.52		0.49		0.46		0.43		0.40		0.38		0.35
8.2	1.3		1.2		1.2		1.1		1.0		0.96		0.90		0.84	0.79		0.74		0.70		0.65		0.61		0.57		0.54		0.50	0.47		0.44		0.42		0.39		0.37		0.34		0.32		0.30
8.3	1.1		1.1		0.99		0.93		0.87		0.82		0.76		0.72	0.67		0.63		0.59		0.55		0.52		0.49		0.46		0.43	0.40		0.38		0.35		0.33		0.31		0.29		0.27		0.26
8.4	0.95		0.89		0.84		0.79		0.74		0.69		0.65		0.61	0.57		0.53		0.50		0.47		0.44		0.41		0.39		0.36	0.34		0.32		0.30		0.28		0.26		0.25		0.23		0.22
8.5	0.80		0.75		0.71		0.67		0.62		0.58		0.55		0.51	0.48		0.45		0.42		0.40		0.37		0.35		0.33		0.31	0.29		0.27		0.25		0.24		0.22		0.21		0.20		0.18
8.6	0.68		0.64		0.60		0.56		0.53		0.49		0.46		0.43	0.41		0.38		0.36		0.33		0.31		0.29		0.28		0.26	0.24		0.23		0.21		0.20		0.19		0.18		0.16		0.15
8.7	0.57		0.54		0.51		0.47		0.44		0.42		0.39		0.37	0.34		0.32		0.30		0.28		0.27		0.25		0.23		0.22	0.21		0.19		0.18		0.17		0.16		0.15		0.14		0.13
8.8	0.49		0.46		0.43		0.40		0.38		0.35		0.33		0.31	0.29		0.27		0.26		0.24		0.23		0.21		0.20		0.19	0.17		0.16		0.15		0.14		0.13		0.13		0.12		0.11
8.9	0.42		0.39		0.37		0.34		0.32		0.30		0.28		0.27	0.25		0.23		0.22		0.21		0.19		0.18		0.17		0.16	0.15		0.14		0.13		0.12		0.12		0.11		0.10		0.09
9.0	0.36		0.34		0.32		0.30		0.28		0.26		0.24		0.23	0.21		0.20		0.19		0.18		0.17		0.16		0.15		0.14	0.13		0.12		0.11		0.11		0.10		0.09		0.09		0.08